1. Field of Invention
The invention relates to a control system and method for a motor vehicle. More particularly, the invention relates to a control system and method for a motor vehicle including an internal combustion engine and a motor connected to an output shaft of the internal combustion engine.
2. Description of Related Art
Of such control systems, for example, Japanese Laid-opened Patent Publication No. 2000-297668 discloses a control system which controls engine speed using a motor generator during engine start while prohibiting idle speed control of an internal combustion engine, thus preventing interference between the idle speed control and the engine speed control with the motor generator.
With this control system, however, although interference between the idle speed control and the engine speed control does not occur when controlling the rotation speed of the output shaft of the internal combustion engine, abrupt changes in torque (i.e., torque shocks) may occur at the output shaft during an engine start. Namely, the internal combustion engine acts as load on the output shaft when cranked by the motor generator. After the engine has started, however, the engine starts serving as a driving power source outputting torque to the output shaft. Thus, it is likely that torque shocks occur at the output shaft during an engine start.